The present invention relates to a secondary air injection system for improving emissions of internal combustion engines and an engine cylinder head and exhaust system designed to be used with or without a secondary air system.
During the combustion process, gasoline is combusted and oxidized. More specifically, hydrogen (H) and Carbon (C) components of gasoline combine with components of air, specifically nitrogen (N2) and oxygen (O2), to generally form various chemical components, including carbon dioxide (CO2), water (H2O), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), and unburned hydrocarbons. In today's vehicles, the exhaust of internal combustion engines is passed through a catalytic converter to reduce emissions. The catalytic converter reduces the unburned hydrocarbons and carbon monoxide (CO), as well as other harmful components of the exhaust, to reduce emissions by acting as a catalyst to complete the reaction of exhaust components to water vapor and carbon dioxide (CO2).
To improve the efficiency of catalytic converters and to complete the combustion process, some vehicles include a secondary air injection system. Secondary air injection systems typically include an air source and a method for injecting air into the exhaust system, typically directly into the exhaust manifold, exhaust header or catalytic converter of an internal combustion engine. The air source is usually an air pump and injects air into the exhaust stream through the exhaust manifold or exhaust headers and is strong enough to overcome the exhaust pressure of the engine. The secondary air injection system also helps on cold start-ups by heating the catalyst of the catalytic converter by further completing the reaction of certain exhaust components to improve emissions while the vehicle is still at a cold operating temperature.
One problem with existing secondary air systems is that the air injection still occurs some distance from the combustion chamber and therefore after a cold start, the effect of the secondary air system may take a longer than desired to operate efficiently. Today, one area of concern is the emissions produced by an internal combustion engine immediately after start-up. Another problem with secondary air systems is that they generally require special exhaust manifolds or special exhaust headers that can only be used with secondary air injections systems and not on vehicles that do not include secondary air systems. For example, if an exhaust manifold includes a secondary air injection system, the exhaust could exit the manifold when an air source is not attached, thereby bypassing the catalytic converter, increasing emissions, and placing noxious components of the exhaust, such as carbon monoxide (CO), in the engine compartment.
Therefore, there is a need for a secondary air injection system that improves efficiency of the combustion of exhaust components quickly on cold start of an internal combustion engine, as well as a secondary air system that uses components that may easily be interchangeable with vehicles not having a secondary air injection system. Further, there is a need for a system that allows for easy conversions of vehicles not having secondary air systems, to vehicles that do have secondary air systems, such as when emissions need to be reduced in a vehicle that has been imported into another area with stricter emission standards.